Itch.io platform is incredible place that collects a lot of incredible games and needs a lot of work to support. So, maybe original text must be paraphrased -- "not overwhelmingly customizable toolset".

Even with basic banner, background and color editing + gifs you can get branding done. There is nothing inherently wrong to email support, aren't there? If you have some serious project going on you obviously will contact support staff one way or another. Moreover. Give all the tools to user and Itch.io will lose all the layout guidelines and, with it, consistency.